A process-based, biological model is presented that simulates soil nitrogen (N) mineralization and nitrification in two northern hardwood forest ecosystems in the Upper Peninsula of Michigan. The soil system is divided into two compartments (forest floor and mineral soil) since quantity and quality of the organic substrate, and the important driving variables (temperature and moisture) for the model vary between these two compartments. The model focuses on the central position of microorganisms in the N mineralization and nitrification processes, and the use of multiplicative factors to account for the effect of temperature, moisture and carbon(C):N ratio on these processes. The model has been validated with data from two northern hardwood stands in the Upper Peninsula of Michigan. A close agreement between calculated and observed monthly means was obtained in both stands, especially for net N mineralization, which plays a very important role in determining available N. The nitrification rates had relatively larger variation than the N mineralization rates, but the model adequately described the seasonal trends of the observed values. A simple sensitivity analysis was performed to assess the response of the model to changes in important variables (temperature, moisture, organic N, and C:N ratio) between the two study sites. This analysis showed that increased temperature and higher organic N levels consistently increased N mineralization and nitrification in the both stands. The model’s results were most sensitive to moisture changes in forest floor, but were not sensitive to moisture changes in the mineral soil. In contrast, C:N ratio was influential in the mineral soil, but did not have any effect in the forest floor.
Laws of annual nutrient uptake of 8-yr.-old paulownia (Paulownia Sieb. et Zucc) plantation (spacing in row 6m, row spacing 10m) in Fengqiu paulownia experimental spot in Huanghuaihai plain was studied for 2 years by using scientific methods and became clear. Annual total uptakes of 5 macronutrients (N, P, K, Ca, and Mg) in 1989 and 1990 were 287.3238 and 242.4234 Kg/hm2 · a respectively. The study found the following laws; (1) the nutrient uptakes of different paulownia organs came in the following order: foliag> branches> flowers> stems> roots; (2) the uptake of different nutrient elements came in the following sequence: N> Ca> K> P> Mg; (3)paulownia’s uptake rate of nutrient elements was mainly conducted during the period between the beginning of growth and the end of July.
The cutting propagation technique ofPicea koraiensis was carried under automatic spraying of total sunlight by adopting the same year epicormic branches from different trees with different age treated by different hormones in different concentration and time and the orthogonal and randomized block was designed. The results were as follows: (l)The rooting rate of the cutting reached at least 87 percent, when the cuttings were from the seed tree with the age below 25 years old and the cuts of the cuttings base were in vertical angle and on the fine sand medium. (2) The sequence of effective factors affecting the rooting rate were the style of cut, the age of seed tree and the type of medium. (3) There are significant differences of rooting rate among different clones.
The regional forest resource structure was analyzed and a dynamic simulation model of management forest resource system was set up. By this model, different changeable results of forest resource in Mudanjiang District of Heilongjiang Province were simulated and analyzed under different management policies using of computers. Then an optimum management forest resource plan was selected. In addition, it also provides an effective theoretical basis for decision maker to draw up a precise development forestry strategic plan for some region.
The broad sense overlap concept and types of tree crown overlap were defined in the paper through analyzing function between the factors of tree crown overlap. The formulas of overlap area and overlap rate were derived from definite integral form. At the same time, many formulas were acquired while the projective figures of tree crown were circle. Application ways of these formulae were illustrated with a concrete caculation process.
Based on the theory of forest burning link, the combustibility of the 6-year-old Chinese fir (Cunninghamia lanceolata) and macclure michelia (Michelia macclurei) mixed forest was determined in Youxi County, Fujian Province from 1988 to 1989. The results show that the daily mean moisture in the forest, moisture content of litter and the water reserves of the stand in mixed forest are 3%, 7.6% and 46.8% higher than that in pure stand respectively, the inflammables quantity and energy ratios of the stand biomass and total potential energy in mixed stand are 8.5% and 3.69% lower than that in pure stand respectively. Mixed forest can decrease the combustibility of stand.
Based on the fire statistics, the Daxing’anling forest area were classified into three fire cycle regions: northern coniferous virgin forest region with a fire cycle ofl 10–120 years, middle conifer-broad-leaved mixed forest region with a fire cycle of 30–40 years, and southern broad-leaved secondary forest region with a fire cycle of 15–20. The percentage of conifers and broad-leaved trees, forest age and natural mature period of main tree species in different fire cycle regions were discussed in concern with fire occurrence. The characteristics of fire adaptation and fire resistance of main tree species, such as sexual and asexual reproduction, were discussed and evaluation of the synthetical fire adaptation was made.
A large areas of Larch seedlings, including container and bare-root seedlings (new and transplanted seedlings) were inoculated pure inocula that were cultivated by usingSuillus grevillei. Compared with those of control area, all growth indices as rate of emergence, growth(in seedling height, collar diameter and number of lateral branch-root), rate of mycorrhiza inoculum, rate of survival and content of nutrient elements were greatly increased. Therefore,Suillus grevillei is a better and suitable mycorrhizal fungus to larch seedling either in the severe cold mountain area or in the plain region. It should be spread and used in larch cultivation and planting.
A distribution map of osier weevil (Crytorrynchus lapathi L.) was drown up based on widely collecting information and field survey. The results showed that Osier weevil has a widespread in China, stretching from 33°21’ to 51°42’ N latitude and 83°00’ to 132°58’ E longitude, and distributes in forms of big or small patches or sports uncontinously. According to the analysis of meteorological data, the temperature and humidity threshold for osier weevil’ s distribution were determined by methods of PCA (Principle Component Analysis) and RA(Relativity Analysis): January temperature is -30∼ 0°C. Annual temperature -4∼13°C, Annual precipitation from 411∼ 1,136 mm. The areas with January temperature under 0°C., annual temperature above 0°C and annual precipitation of 400∼ 800 mm are the optimum distributing places for osier weevil in China.
The control ofColeophora dahurica Flkv. by ULV spraying rare oil of malathior was popularized in Inner Mongolia Daxing’an Mountains in 1992–1993. The control area was 32744.3 hm2, which was 98.2% of the suitable control area in Inner Mongolia Daxing’an Mountains and 75% of the suitable area in Inner Mongolia respectively. Dosage was 1125 g/hm2. Control effectiveness was above 95%; the larvae density decreased from 52.5 to 0.94 per 50cm sample twig and direct economical benefit was 3,935,420 Chinese yuan.
An expeditious method for ascertaining species between black bear (Seienarctos thibetanus G. cuiver) and brown bear (Ursus arctos Linnaeus) was developed using tooth measurements from previously identified specimens. The measurement and analysis on 18 tooth measurement indexes (i.e. T1. Length of Pm1-Pm4, T2. L. of M1-M3, T3. M1L., T4. M1 width, T5. M2L., T6. M2W., T7. M3L., T8. M3W., T9. L. of C1 alveolus, T10. W. of C1 alveolus, T11. L. of C1-M2, T12. L. of Pm 4M2, T13.M1L., T14. M1W., T15. M2L., T16. M2W., T17.L. of C1 alveolus, T18. W. of C1 alveolus) of 59 skulls (black bears 25, brown bears 34) indicates that there are significant or the most significant difference between two species in every indexes, however T1, T9, T10, T17 and T18 are not suitable for species discriminator because of their high percent of overlap. The efficient species discriminators and standards (mm) are as follows T2(63.0), T3(22.0), T4(10.2), T5(23.8), T6(13.6), T7(18.0), T8(13.5), T11(110.0), T12(66.0), T13(20.1), T14(15.8), T15(33.0) and T16(17.3). Those who are less than or equal to standard are classified to black bear, the others are brown bear. The method is very convenient and useful with high reliability. Their lowest accuracy percent are 95.0%, most of them over 97%. Different indexes will be chosen refer to the degree of specimen destroyed.
Grey heron (Ardea cimerca) is one kind of the great birds which are often seen in the northeast marsh area of P.R.China, and there are many grey herons to reproduce in Zhalong Nature Reserve from March to August annually. In this paper, through the investigation of the grey heron’s nesting habitat and according to the water depth, vegetation type, cover density and plant height of the nesting place, the grey heron’s nesting habitat suitability index models are established. The main model is s=(s1×s2×s3×s4)1/4, where s1 is the water depth suitability index, S2 is the vegetation type suitability index, S3 is the cover density index, S4 is the plant height suitability index. These models provide a kind of reliable method for evaluating the habitat quality of the grey heron’s nesting.
The karyotype ofArdea purpucea andArdea cinerea, Ciconiifores, are presented in this paper. Chromosome preparations were made from bone marrow cells and stained with Giemsa. The diploid number of chromosome ofArdea purpucea andArdea cinerea are 62 ± and 60 ± respectively. The numbers of macrochromosome of these two birds are same, namely 11 pairs. Among them, six pairs of macrochromosome are morphologically very similar between the two birds.
Four groups of nutrias of 3–4 months old were taken as the experimental animals fed with four diet with different digestion energy. The results are that the diet prescriptions which. contain different digestion energy result in a extremely significant difference in energy digestibility of nutrias.(P<0.0l); the diet prescriptions which contain different digestion energy result in a extremely significant different in crude protein digestibility of nutrias.(P<0.01); the linear relationship presents between different digestion energy and energy digestibility, and the relationship coefficients is 0.8; dE(%)=0.62C(%)-7.18 lnCF(%)+57.78 is the regression equation between energy digestibility and crude fiber and carbohydrate in diets; dE=2985.7+18.10w is the regression equation between weight gaining of nutrias and digestion energy of nutrias; The difference of gaining weight is extremely significant among different groups of nutrias (P<0.01).
Through scanning electron microscope, various types of feathers in various parts of red-crown crane—a kind of rare and precious bird were observed micrographically. It was shown in the result that in different type of feather, the barbules show a great variation in their morphology and structure. This observation can be a basic reference for the taxonomy using the feather structure and the study of systematic relationship.
The paper introduces the situation of studies on sustainable development in the world and China’s response to the topic. The impediments of natural resources to realize sustainable development in China are analyzed. And seven strategies to accomplish this arduous task are suggested.